Mantle Anisotropy in Tierra del Fuego from MT Data: Scotia Arc Development

RUANO, PATRICIA; IBARRA, P.; CEMBROWSKI, MARCEL; BOHOYO, FERNANDO; PEDRERA, ANTONIO; RUIZ-CONSTÁN, ANA; GALINDO-ZALDÍVAR, JESÚS; GONZÁLEZ-CASTILLO, LOURDES; MAESTRO, ADOLFO; TORRES CARBONELL, PABLO; JUNGE, ANDREAS

Davos

Congreso; Polar 2018 SCAR/IASC Open Science Conference. Where the Poles come together; 2018

Scientific Committee on Antarctic Research (SCAR) and International Arctic Science Committee (IASC)

The Scotia Arc was formed by the eastwards migration and dispersion of the continental fragments thatconnected South America and the Antarctic Peninsula. In this process the Drake Passage constituted a narrow gateway that facilitates the eastward flow of the mantle from the Pacific towards the Atlantic. Tierra del Fuego, northwards of Drake Passage, is a key area to study the effect in the upper mantle of this major tectonic event. 18 long period magnetotelluric sites were recorded along 2 profiles using LEMI-417 stations the 3 magnetic and 2 telluric field components in the frequency range of 4 Hz to investigate the deep crustal and upper mantle conductivity. Standard robust processing was performed yielding high quality transfer functions. The interpretation of phase tensor invariants and tipper vectors was undertaken by 3D anisotropic modeling using the Frankfurt group software based on Comsol Multiphysics 5.2?. GEBCO database was considered to take into account the effect of surrounding seawater. A main NW-SE oriented anisotropy is determined in the upper mantle. This anisotropy may be consequence of former mantle anisotropies parallel to the Andes Cordillera rotated during the development of the northern branch of the Scotia Arc. However, the most suitable interpretation suggests that this remarkable anisotropy may be related to the eastwards mantle flow across the Drake Passage during the development of the Scotia Arc.